When you want to quickly capture the business process you might wnat to think about a good ERP/CPRM.
There is a cost to the systems but it does result in very powerful / integrated solutions.
Vertical templates provide a good starting point for defining entities specific to the business.
User's have many interfaces for interaction, web based, UI, outlook plugin with offline support, mobile, webservices.
Built using the .net framework, uses workflow, outlook, exchange to implement the entire system.
Plugins archatexture for eventing with offline support, extenibility add attributes to entities.
Provides serious plumbing for reporting, auth, data services, offline support, and general LOB dev platform.

Microsoft CRM CALs are used for licensing.
Microsoft CRM does not include anything for accounting at this point.
CRM backend usage ->
push to sharepoint for collaboration (on fly) ->
outside people come in view/modify ->
using WF, event and push back into CRM (remove sharepoint site too possibilty).

BizTalk is a publish subscribe messaging engine at its core.
It also includes an orchestration engine, to manage and model long running work.
Durable messaging with store and forward capabilities.
BizTalk has roots in integration of enterprise systemstrace of thought (Scott Colestock) - a trace of thought on...BizTalk Server, Team Foundation Server, Windows Mobile, etc.